1. Field of the Invention
The invention relates to a scroll saw, more particularly to a scroll saw with a saw blade fastening and tension adjusting device that facilitates attachment and removal of a saw blade.
2. Description of the Related Art
FIG. 1 illustrates a saw blade fastening and tension adjusting device of a conventional scroll saw 10. The device comprises an adjustment unit 11 which is mounted on a distal end of an upper arm (12a) of the scroll saw 10 and which includes a rotary knob 111 and a connecting post 112. The connecting post 112 has an upper portion which is connected threadedly to the rotary knob 111 and a lower portion which extends through an upright hole 121 in the upper arm (12a) and which carries an upper blade holder clip 141 thereon. A compression spring 15 is provided around the lower portion of the connecting post 112 and is disposed between the upper arm (12a) and the upper blade holder clip 141. A lower blade holder clip 142 is mounted on a distal end of a lower arm (12b) of the scroll saw 10. A saw blade 13 extends between the upper and lower blade holder clips 141, 142 and has two ends which are retained removably by the latter.
The rotary knob 111 is rotated in a first direction in order to move the connecting post 112 and the upper blade holder clip 141 upwardly, thereby compressing the compression spring 15. The distance between the blade holder clips 141, 142 increases, thereby increasing the tension of the saw blade 13. When the rotary knob 111 is rotated in a second opposite direction, the connecting post 112 and the upper blade holder clip 141 move downwardly, thereby causing the compression spring 15 to expand. The distance between the blade holder clips 141, 142 is decreased, thereby loosening the tension of the saw blade 13 so as to permit removal of the saw blade 13 from the blade holder clips 141, 142.
Note that in the above described device, quick attachment or removal of the saw blade 13 is not possible because of the need to rotate the rotary knob 111 before the upper blade holder clip 141 can be moved toward or away from the lower blade holder clip 142. Likewise, proper adjustment in the tension of the saw blade 13 cannot be conveniently conducted because of the above reason.